Anneli Auranen, Master Student in Textile, Aalto University has been involved in wool recycling project. The research aimed at creating connections with different wool actors and connect the supply chain for wool recycling in Finland. Another aim was to research the suitability of recycled wool for a variety of products and see what kind of business potential there is in wool recycling. They also studied fiber properties and chemical residues in recycled wool.
The project was coordinated by Metropolia University of Applied Sciences but several companies involved in the wool/textile industry participated.
The mechanical recycling process of wool includes collecting, sorting, shredding, carding, spinning, garment production, transporting, storage, sales and using – including repairing and reusing. Spinning into yarn can be done only once as the fibre length is shortened during shredding.
Collecting for the project was done by Reuse centre in Helsinki. Knitwear and old textiles with a minimum of 75% wool was collected. Sorting was made according to colour and fibre content. The materials is not always so easy to tell if labels are missing. Sorting was labour-intensive, as removing hard parts like zippers, buttons etc. was manually done. They also used waste from the wool industry which is easier to sort.
Shredding means to tears textiles apart into fibres that can be used again. The next step is opening and mixing with virgin fibres. Carding straightens the fibers and removes trash and tangles. During carding the fibres are turned into batts, thin sheets or a long strip. Spinning of recycled wool fibresisthe same process as with new wool with the exception that you cannot spin worsted yarn due to the uneven quality of fibres. It is also difficult to produce thin yarn from recycled fibers but in Italy they can make thinner yarn than made in this project.
The fibre length of recycled fibers varied between 25-53 mm. This is good compared to the fibre length of virgin wool (25-75 mm). The fiber composition of 80 % recycled wool /20 % virgin wool had the average fiber length of 47mm, which performs well in all production stages.
It is important to analyse if there are chemical residues in recycled wool. When the material was tested for formaldehyde it contained 4-22 mg per kg which is under the limit allowed for textiles for children. Other tests were done and they didn’t find anything alarming, but more tests are needed.
The results from the study shows that recycled wool performed well in all production stages! The current problem is that there is no organized collection and sorting of the material in Finland. There is however a project called Telaketju in Finland that organizes textile collecting and sorting by 2023.
All final products are grey, as there were not enough textiles for sorting in different colours. The amounts of wool waste in Finland are relatively small so cooperation with other countries could be beneficial for larger scale business.